first=float(input("请输入第一个数:"))
second=float(input("请输入第二个数"))
operator=input("请输入运算符:+ -*/:")
if operator=='+':
    print("first+second")
elif operator=='-':
    print(first+second)
elif operator=='*':
    print(first*second)
elif operator=='/':
    if second==0:
        print("除数不能为0")
    else:
        print(first/second)
